Driving and non-driving hub and wheel bearing assemblies of an automotive vehicle require a preload to be imparted upon the wheel bearings in order to align and retain the hub and wheel bearings. The preload is accomplished by using an axle washer that is forced against a wheel hub by an axle nut. The axle nut has internal threads that engage the external threads of a shaft of an outboard drive axle. The shaft is axially coupled to an outer race of a constant velocity joint. A wheel bearing assembly typically includes an outer bearing race and two separable inner races rotatably coupled by two sets of bearings, each set of bearings being thrust against the outer bearing race by its inner race. The outer bearing race is fixedly attached to a vehicle's frame, for example the bearing support or steering knuckle of a motor vehicle. The inside inner race is supported against the outer race of the constant velocity joint axially coupled to the shaft. The outside inner race is supported against the wheel hub and is axially coupled to the shaft or the wheel hub. The wheel hub transfers the preload force through the outside inner race into the bearings and outer bearing race. The preload force is opposed in the opposite direction by the outer race of the constant velocity joint through the inside inner race into the bearings and outer bearing race thus supporting and aligning the hub and wheel bearings when a preload is applied by the axle nut.
The preload may also be applied by using a wedge or spacer that fills a gap on the end shaft when the hub is preloaded against the bearing assemblies and the wedge or spacer is fit into the gap to maintain the preload. Other methods have also been employed for obtaining the pre load on the hub and bearing assembly, such as using a head of a bolt that is threaded into the axial end of the shaft and torqued against the axle washer or hub.
To insure that the preload is maintained, the axle nut is assembled with a lock nut, cotter pin or other similar methods known for securing nuts onto rotating shafts. A method of securing the preload typically requires a threaded shaft having a hole drilled radially within, an axle nut with corrugated recesses, an axle washer and locking pin. The locking pin engages the corrugated recess of the axle nut and is inserted into the hole of the threaded shaft locking the axle nut to the shaft. Alignment typically is required in order to install the locking pin and the locking pin is only attachable in incremental steps. In order to attach the locking pin it is sometime necessary to either increase or decrease the preload by adjusting the axle nut upon the shaft. This results in varying inconsistencies in the preload of each bearing assembly.
The preload is imparted during assembly of the wheel hub and wheel bearings onto the shaft. Using a torque wrench or other torque device, the axle nut is threaded onto the shaft against the assembly until a given torque range is obtained. The axle nut, typically, is then rotated back relieving some of the torque and locked into place.
It would be advantageous to have a shaft that is not threaded and eliminates the need for an axle washer and axle nut, or bolt, while still being able to retain the hub and wheel bearing assembly. It would be of further advantage to have an assembly that requires no preload or no lock nut adjustment. Also, it would be of advantage to eliminate the torque assembly procedure.